The proposed research tests the hypothesis that differences in sleep mentation can be accounted for by shifts in the relative "dominance" of the two hemispheres during sleep. The hypothesis will be tested by obtaining mentation reports from stages REM and 2 (NREM). Hemispheric dominance will be assessed by measuring bilateral EEG integrated activity. This technique has been shown in a number of studies to reflect hemispheric function during waking. Mentation reports will be rated on characteristics such as vividness of imagery, conceptual thought, and bizarreness. In the first (exploratory) stages of the project, ratings will be correlated with EEG activity from right and left temporal and parietal sites, using Fourier analysis to analyze various bandwidths. After identifying the most promising combination of bandwidth and sites, Ss will be awakened in the second stage of the study according to a pre-selected EEG asymmetry criterion during REM and Stage 2 (computed on-line) to test the dominance model of dreaming. Our goal is to provide a general model (i.e., one which is relevant to sleep and waking mentation) which can both account for variance unexplained by existing models of sleep mentation and offer a mechanism for the varieties of mentation during sleep.